The present invention relates to floor systems for athletic use and, more particularly, to a cushioned floor system of modular construction which is completely portable.
Floor systems used in athletic, sport, and recreational facilities, such as gymnasiums, arenas, roller skating rinks, dance and exercise studios, and the like, often utilize hardwood flooring. Such flooring generally comprises long and relatively narrow hardwood boards, typically mounted in interlocking engagement with a conventional tongue and groove construction as is well known in the art. The hardwood surface flooring may be supported on a base surface, such as a concrete slab, in a variety of ways. However, the floor is typically categorized as either fixed or floating. As the terms imply, a "fixed" floor is attached directly to the base concrete slab with an intermediate supporting layer or layers, and a "floating" floor lies on the base slab, separated by intermediate layers of various materials, but without direct attachment to the slab.
Floating floor systems, in particular, are often constructed with resilient intermediate layers which result in a cushioned floor system providing varying degrees of surface flexibility. It is well known that cushioned floor systems provide substantial benefits to users of sport and recreational facilities utilizing such floors. Resilient or cushioned floors which help absorb the shock to the user resulting from vertical impacts by the user on the floor, not only reduce fatigue and the chance of injury, but provide a vertical spring-back which may enhance athletic performance.
Thus, cushioned floor systems providing some degree of vertical flexibility have been proposed in a variety of constructions utilizing both conventional hardwood top flooring and a variety of other surface materials. However, high quality hardwood flooring must be carefully installed and maintained and properly cushioned to maintain its quality and performance. By comparison, other athletic surfaces are not generally as sensitive to the type and quality of subflooring materials, including resilient cushioning devices.
It is also known to make athletic and recreational floors of a modular construction in which prefabricated modules are laid side by side on a supporting base and interconnected to form a continuous floor surface. Modularity not only facilitates initial installation, but in some cases may be desirable to allow the floor to be subsequently disassembled and removed, to, for example, provide for installation of a different surface or to adapt the facility to another use. However, modularity in flexible cushioned floor systems requires more care in protecting the flexible cushioning means which are, in general, more susceptible to damage than the harder and more rigid wood or wood-base components. In addition, modular constructions utilizing quality hardwood floor surfaces must also be carefully constructed so the inherent additional handling is not detrimental to the integrity of the floor surface.
In U.S. Pat. No. 4,648,592 (Harinishi), there is disclosed a modular cushioned athletic floor. Each module comprises a unitary panel board piece having resilient compressible foam supporting members attached to the underside to rest directly on the underlying base surface (e.g. concrete slab). The modules are interconnected with special edge connectors and a continuous top playing surface comprising a composite of foam supported carpet is laid over the modules. As a result of either installing or dismantling the floor system, the relatively delicate foam supporting members, which are preferably made of ethylene vinyl acetate foam and bear directly on the base surface, are readily susceptible to damage. Positioning the modules may result in lateral movement which can scuff and damage the compressible foam supports or tear them from their attachment to the panelboard module. The compressible supporting members are also relatively unprotected against dirt, moisture and the like which may be present on the concrete base surface.
U.S. Pat. No. 3,604,173 (Dahlborg) discloses a resilient athletic floor, also of the floating type, in which two separate layers of compressible resilient pads are attached to opposite sides of an intermediate floor panel of particle board or plywood with the lower layer of resilient pads lying on the base surface and the upper layer supporting another fiber or particle board layer covered with a surface of linoleum mat, vinyl tiles, or the like. The floor is not modular and is intended for permanent installation. Nevertheless, the lower layer of resilient pads which bears directly on the supporting base slab is unprotected, either from potential damage during installation or environmental conditions encountered thereafter.
In U.S. Pat. No. 2,862,255 (Nelson), a conventional tongue and groove hardwood floor construction is disclosed utilizing typical wooden sleepers to support the flooring, but providing a cushioned, floating installation by attaching flexible cushions in a spaced orientation to the undersides of the sleepers. The flexible cushions, which are made of rubber or another suitable elastomer, bear directly on the concrete slab or other base surface. Although the floor system described in this patent is intended for permanent installation, the resilient supporting cushions are directly exposed and relatively unprotected.
U.S. Pat. No. 4,325,546 (McMahon et al) discloses an athletic floor module comprising upper and lower floor plates of wood or other stiffly resilient material which are held in spaced parallel relation by a small rigid spacer attached to both plates and disposed generally in the center of the plate areas. Compressible resilient members are disposed between the plates, generally along the periphery and in a symmetrical pattern around the center spacer. The module is supported above the underlying base surface by a rigid peripheral frame. Live loads on the central portion of the module cause concurrent vertical deflection of the interconnected upper and lower plates, while loads applied further from the center and toward the peripheral edges cause compression of the resilient members and vertical deflection of the upper plate toward the lower plate. Proper choice of plate, spacer, and resilient materials, and their sizing, orientation and spacing, is intended to provide a floor module with uniform vertical deflection over the entire upper plate surface. As an integral part of the foregoing construction, hold down bolts extending between the plates are used to prevent upward movement of one peripheral edge of the upper plate as a result of a downward impact force on an opposite peripheral edge, yet permit vertical deflection of the upper plate as indicated above.
The module disclosed in McMahon et al and a floor constructed of such modules inherently requires two modes of flexibility for proper function, i.e. a simultaneous bending of both spacer-connected plates and a separate deflection of the upper plate toward the lower. Uniformity of deflection requires careful choice and balancing of the material types, and sizing, orientation and spacing of the various components. The construction of the module of the preferred embodiment includes an upper plate of plywood covered by a thin polyurethane layer and is particularly intended for use as a running track, although other athletic applications are also suggested. Although such an upper surface may be suitable for a flexible floor system utilizing the bimodal flexibility described above, such a system is not considered suitable for use with conventional hardwood flooring.
U.S. Pat. No. 3,422,732 (York) shows a flexible artificial ski mat having sheet-like upper and lower surfaces of flexible rubber separated by a layer of resilient compressible foam. The upper surface is intended to deflect toward the lower under live load and anti-friction supporting elements on the top surface are, in one embodiment, attached with bolts recessed and anchored in the foam layer to accommodate vertical movement of the upper surface toward the lower. In that construction, however, the bolts merely hold the anti-friction elements in place and do not restrict relative movement between the upper and lower surfaces or provide any resistance to horizontal displacement as a result of lateral shear forces.
A relatively recent development in floating cushioned floor systems utilizes small elastomer pads which are uniformly distributed in spaced relation across the underside of the floor to support it above the underlying base surface. The elastomer pads provide two stages of compressibility, one to carry the dead weight of the floor and light live loads as are imposed by walking, and the other to absorb heavier shock loads resulting from running, jumping or falling. This floor system is sold under the trademark "NEO-SHOK" by Conner Forest Industries. However, such floor systems do not utilize a modular construction and have been limited to relatively large permanent installations. The shock absorbing elastomer pads must be fastened to the underside of the floor, typically by gluing or stapling. With either method of attachment, it is generally known that the elastomer pads are not tolerant to horizontal shear loads and, as a result, movement of floor panels and attached pads across the subfloor may result in damage or displacement of the elastomer pads. Thus, the floor system does not inherently lend itself to portability even though a portable cushioned athletic floor has potentially broad applicability and use. For example, a portable floor which has an attractive, durable and functional surface and which uses modules that are easy to assemble and disassemble could be used in aerobic exercise and dance facilities, athletic shoe stores, and similar installations where floors of relatively small area are typical. True portability would also allow such a floor to be moved from one location to another and to be maintained as personal property. In particular, portable floor systems utilizing high quality hardwood flooring would be particularly attractive for many such applications. However, where elastomer cushions and shock absorbing pads are used, the pads must also be protected against dirt, moisture and other contaminants, as well as scuffing, tearing or displacement as a result of lateral shear loads. Such hazards are especially acute where the added movement and handling of a portable floor are present.